Relapse in CLL can be mediated by at least two separate mechanisms. One is by mutations in BTK, the other is through a variety of mutations in the immediate downstream target of BTK, PLCγ2. SNX-5422 is a prodrug of SNX-2112, a potent, highly selective, small molecule inhibitor of the molecular chaperone heat shock protein 90 (HSP90). Hsp90 inhibitors may overcome ibrutinib resistance in Mantle cell lymphomas and this study will investigate whether the addition of SNX-5422 to an established dose of ibrutinib will provide clinical response in subjects who have residual disease, but have not progressed on ibrutinib after 18 months of monotherapy.